One of my all-time favourite manga is Petshop of Horrors, a manga created in the 90s, which depicts a mysterious petshop located in Los Angeles' Chinatown, which gives people exactly the pet they need (sometimes what they need is to get eaten alive, so, you know, ymmv).  

As soon as I started reading this book about a mysterious "psychiatric clinic" located in Kyoto where patients are prescribed a cat to help cure what ails them, I had immediate Petshop of Horrors vibes. There are far less people getting eaten alive by their new pets, but still, I'd be surprised if Syou Ishida hadn't read Petshop of Horrors at some point in their life.

Anyway, I loved this a lot. Very sweet. Probably not the best recommendation to anyone who intends to read it in public and has recently lost one of their feline life-companions, but I loved this story a lot.